1 files changed, 50 insertions, 3 deletions
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index cbc95dc643d..e0272a0eb63 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -6171,6 +6171,34 @@ static bool isDeclUnavailable(Decl *D) {
   return false;
 }
 
+static const AvailabilityAttr *getAttrForPlatform(ASTContext &Context,
+                                                  const Decl *D) {
+  // Check each AvailabilityAttr to find the one for this platform.
+  for (const auto *A : D->attrs()) {
+    if (const auto *Avail = dyn_cast<AvailabilityAttr>(A)) {
+      // FIXME: this is copied from CheckAvailability. We should try to
+      // de-duplicate.
+
+      // Check if this is an App Extension "platform", and if so chop off
+      // the suffix for matching with the actual platform.
+      StringRef ActualPlatform = Avail->getPlatform()->getName();
+      StringRef RealizedPlatform = ActualPlatform;
+      if (Context.getLangOpts().AppExt) {
+        size_t suffix = RealizedPlatform.rfind("_app_extension");
+        if (suffix != StringRef::npos)
+          RealizedPlatform = RealizedPlatform.slice(0, suffix);
+      }
+
+      StringRef TargetPlatform = Context.getTargetInfo().getPlatformName();
+
+      // Match the platform name.
+      if (RealizedPlatform == TargetPlatform)
+        return Avail;
+    }
+  }
+  return nullptr;
+}
+
 static void DoEmitAvailabilityWarning(Sema &S, Sema::AvailabilityDiagnostic K,
                                       Decl *Ctx, const NamedDecl *D,
                                       StringRef Message, SourceLocation Loc,
@@ -6268,7 +6296,7 @@ static void DoEmitAvailabilityWarning(Sema &S, Sema::AvailabilityDiagnostic K,
   if (K == Sema::AD_Deprecation) {
     if (auto attr = D->getAttr<DeprecatedAttr>())
       Replacement = attr->getReplacement();
-    if (auto attr = D->getAttr<AvailabilityAttr>())
+    if (auto attr = getAttrForPlatform(S.Context, D))
       Replacement = attr->getReplacement();
 
     if (!Replacement.empty())
@@ -6297,8 +6325,27 @@ static void DoEmitAvailabilityWarning(Sema &S, Sema::AvailabilityDiagnostic K,
     S.Diag(UnknownObjCClass->getLocation(), diag::note_forward_class);
   }
 
-  S.Diag(D->getLocation(), diag_available_here)
-      << D << available_here_select_kind;
+  // The declaration can have multiple availability attributes, we are looking
+  // at one of them.
+  const AvailabilityAttr *A = getAttrForPlatform(S.Context, D);
+  if (A && A->isInherited()) {
+    for (const Decl *Redecl = D->getMostRecentDecl(); Redecl;
+         Redecl = Redecl->getPreviousDecl()) {
+      const AvailabilityAttr *AForRedecl = getAttrForPlatform(S.Context,
+                                                              Redecl);
+      if (AForRedecl && !AForRedecl->isInherited()) {
+        // If D is a declaration with inherited attributes, the note should
+        // point to the declaration with actual attributes.
+        S.Diag(Redecl->getLocation(), diag_available_here) << D
+            << available_here_select_kind;
+        break;
+      }
+    }
+  }
+  else
+    S.Diag(D->getLocation(), diag_available_here)
+        << D << available_here_select_kind;
+
   if (K == Sema::AD_Partial)
     S.Diag(Loc, diag::note_partial_availability_silence) << D;
 }